This invention relates to a blank for making a box of carboard, corrugated board or other sheetlike material and, more particularly, to a blank for making boxes which can be stacked upon similar boxes.
Blanks for forming stackable boxes are known. In one such construction, inner and outer end pieces define a narrow, vettical opening, the box also being provided with an upwardly extending flap. The size of the vertical opening is such that the flap in the lower box is pushed into the narrow opening of the upper box upon stacking. In particular, an opening is defined between the bottom and end wall of the box, an upwardly extending flap being formed by a suitable cut in extensions integrally formed with the end wall. The boxes are constructed by folding side wall extensions which are shorter than the bottom of the box along straight creases which define the extension. Thereafter, the end walls of the boxes together with the extensions thereof are folded over the folded extensions of the side walls, whereby the end walls form the outer end of the box and the end wall extensions form the inner ends of the box. The upwardly extending flap formed in the extensions of the end wall serve to lock the end construction in the opening defined between the bottom and end walls of a box stacked over the lower box.
However, stackable boxes typified by the construction described hereinabove have been found to be not entirely satisfactory. In the case of the structure described hereinabove, the upwardly extending flaps must be precisely manually guided into the narrow openings in the end construction of the boxes upon stacking. Further, it has been found that boxes formed according to prior art techniques can not be reliably stacked, i.e., such an assembly of stacked boxes have been found to be not entirely stable.